In standing water, swimming pools, hot tubs and spas, it is necessary to filter and recirculate water, add chemicals to keep the water safe for bathing or free from algal growth, and remove impurities. It is particularly important to keep standing waters clean for safe use and free from growth of unwanted biological organisms.
As a part of basic pool and water maintenance, it is frequently the case that the water is treated with halogen chemicals, particularly chlorine and bromine. Some bodies of water may be treated with chlorine gas which is dangerous and difficult to use. There is always the danger of exposure of humans or animals to the chlorine gas.
For smaller bodies of water, chlorine is typically purchased and used in the form of calcium hypochlorite granules which may be mixed with water to form a liquid and then poured into the swimming pool. Although such techniques of chlorine dispersion and chemical treatment of water are widespread, there are many disadvantages associated with these methods. In particular, the chlorine is positioned and dispensed near the top of the pool thereby making the treatment inefficient as chlorine evaporates from the surface of the water at a high rate. Furthermore, the process of mixing chlorine granules generally requires the use of buckets and there is a substantial risk of splashing highly chlorinated water, which can cause damage to clothing, discoloration of surrounding areas such as ceramic tile or vinyl, and physical irritation to lungs, eyes and skin due to the caustic fumes.
Another problem associated with the distribution of chemicals in swimming pools, hot tubs, spas and standing water systems, is the actual handling of the chemicals themselves. Most water treatment chemicals are present in granular or powder form, and must be scooped, dissolved, and subsequently distributed. Chemicals which are available in solid or block forms must also be handled, and placed into appropriate devices for distribution. It is generally not feasible to provide pool chemicals or water treatment chemicals, especially chlorine, in liquid form for simplified distribution as this may decrease shelf life or storage options. Consequently, most individuals handling pool or water chemicals must wear suitably protective clothing such as gloves and protective eyewear. Such precautions make chemical treatment of water both tedious and cumbersome. Additionally, many water treatment chemicals are flammable and must be stored to prevent accidental combustion.
Sodium tetraborate has long been known to be effective as an algaecide and a fungicide in standing water systems such as swimming pools, drinking water reservoirs, and cooling towers and is the subject of U.S. Pat. Nos. 4,594,091 and 5,131,938, both to Girvan, both of which are incorporated herein by reference in their entirety. It has been found that the alkaline metal, tetraborate, by itself improves the treatment of standing water systems in several ways. The tetraborate solutions plus dissolved carbon dioxide produce sodium carbonate plus sodium bicarbonate, thereby lowering the CO.sub.2 concentration in the water and making it difficult for algae to germinate in the water. The tetraborates have also been shown to react with dissolved halides in the water to give off free halogen. Finally, the tetraborates increase the solubility of most other salts that may be added to the standing water system.
Another additive that is commonly used to treat standing water is calcium hypochlorite. Calcium hypochlorite is added to water and, when dissolved in water, provides a source of chlorine for disinfectant purposes and for general sanitation. Several commercial processes are currently used for the manufacture of the so-called "high-grade" calcium hypochlorite compositions containing at least 65% calcium hypochlorite from which the chlorine for sanitation purposes is derived. Several of these processes are described in U.S. Patent No. 3,793,216 which is incorporated herein by reference in its entirety.
The '216 patent discloses a calcium hypochlorite composition comprising at least 55% calcium hypochlorite mixed with water soluble, hydrated inorganic salts in an amount sufficient to provide a water content in the total mixture in the range of about 3% to about 13%. Included in the disclosure, as one of the hydrated inorganic salts, are the salts containing tetraborate. The focus of the '216 patent is to reduce the flammability of the calcium hypochlorite.
The major disadvantage of the essentially water-free calcium hypochlorite compositions is the danger intended thereto if contacted by external contaminants, which contamination causes exothermic decomposition of the material regardless of the temperature. For example, if any portion of a batch of said calcium hypochlorite, whether in a small container, large drum or uncontained mass, reaches a temperature of about 350.degree. F., it will undergo a self-sustaining and self-propagating decomposition which will spread through the entire batch until decomposition is complete. Decomposition may be initiated by the accidental touching of a live flame or spark to the calcium hypochlorite composition, as for example, the accidental contact of a lit match or cigarette. Decomposition may also be initiated by contacting the hypochlorite with just a single drop of organic material, for example, glycerin, and alcohol, a variety of hydrocarbons such as petroleum oil and many others. The decomposition of all gaseous chlorine which constitutes a toxic hazard to personnel in the area, and also involves oxygen, which intensifies a fire that might reach stored quantities of calcium hypochlorite. Because oxygen is released in the decomposition process, attempts to smother a hypochlorite fire will be unsuccessful. The '216 patent thus describes a composition which reduces the likelihood of spontaneous decomposition of the calcium hypochlorite composition. However, the '216 patent does not disclose any other properties of a composition comprising calcium hypochlorite and an alkaline metal tetraborate and/or boric acid.
What is needed in the industry is a method of distributing a composition that will stabilize pH of the water, reduce the presence of algae and other microorganisms which normally grow in standing water, and provide a source of halogens which will further sanitize the water solution. More particularly, what is needed is an efficient and safe method of distributing water-treatment chemicals whereby the chemicals are optimally utilized and whereby unnecessary exposure of the chemicals to the persons tending the body of water and the environment is minimized.